Spark plug



ElY E. PASTE RIS Jan. l2, 1932.

SPARK PLUG Filed Dec. 5, 1929 Patented Jan. 12, 1932 UNITED STATES PATENT OFFICE SPARK PLUG Application led December 5, 1929. Serial No. 411,766.

. This invention relates to spark plugs for internal combustion engines, and has for its Vprincipal object the provision of a spark nlug equipped with means adapted automatically to cause the production of an igniting ing a pair of conductors, one conductor connected in an electrical circuit and the other insulated from the former and constituting a firing electrode, a grounded electrode spaced from the liring electrode and defining 1'5 aspark gap for igniting the cylinder charge,

and internal means operable upon the accumulation of gaseous pressure within the cylfinder for electrically connecting the two conductors-thereby to cause an igniting spark at said spark gap when the engine is in firing condition.

Heretofore, spark plugs for multi-cylinder engines of the aforesaid type have usually been connected in an electrical circuit which is intermittently interrupted by a timing device or distributor located in said circuit and arranged to furnish electrical energy successively to the several plugs of the engine 'when the respective cylinders are in firing condition. The operation of such timing devices is ordinarily controlled by the valveoperating mechanism of the engine; the timing mechanism must be carefully adjusted and frequently regulated under varying operating conditions; and it is well known that such mechanism must often be repaired or replaced because of defective operation. The employment of my improved spark plug avoids the use of all such timing devices as well as the wiring and mechanical elements which are essential to their operation; for the several plugs of the same engine may be connected by a common lead to a suit-able source of potential so that a conductor in each plug is continually supplied with current, the current beingv automaticall caused to jump the spark gap by means o mechanism contained within the plug when the respective cylinders arein firing condition.

Further objects of the invention reside in the structure and arrangement of the operative elements of a spark plug constructed in accordance with Athe invention as hereinafter described and illustrated in the accompanying drawings, and as pointed out in the appended claims. In the drawings;

Fig. l is an elevation of the improved plus;

Fig. 2 is an enlarged vertical section thereof, showing the movable elements in normal, inoperative position;

Fig. 3 is a similar View of a portion of the spark plug, illustrating the parts in operative position;

Fig. 4 is a sectional detail showing another position of the parts;

Fig. 5 is a transverse section to larger scale on line indicated by the arrows of F ig. 3*; and

Fig. 6 is a diagrammatic View of an electrical circuit in which the plugs are connected.

The particular embodiment of the invention chosen for the purpose of illustration comprises a metal shell 7 which screws into the wall of the cylinder in the usual manner, a hollow insulating body 8 having an annular shoulder 9 seating upon a complement-al shoulder Within the shell and confined thereupon by a follower nut 10, a metal core 11 fitting within the insulator 8 and having a shoulder 12 abutting a shoulder of the insulator, and a head 18 of insulating material having a reduced neck 14 threading into the core' 11 and carrying an axial conductor 15 which is provided with an outer terminal having a thumb nut 16 for securing a wire or bar connected with a source of electrical energy, and which has its lower end projecting from the base of the neck 14 into a chamber 6 of the core 11. The core 11 constitutes a second conductor or firing electrode and its lower end preferably projects below the bottom of the insulator 8; and a ground electrode 17 iXed to the shell 7 is arranged in spark-gap relation to said base.

The bore of the conductor 11 is preferably uniform in diameter and screw threaded from end to end, the upper end receiving the neck 14, as aforesaid, and the lower end of the conductor 15 being spaced sufficiently from said *bore so that the electrical current furnished to the rod conductor 15 will not jump the gap to the core conductor or electrode 11. Threaded within the lower portion of the core 11, in spaced axial relation, vare a series of collars or short tubes 18, 19 and 20, each having an axial aperture providing a passageway from the open base of the core to the central chamber 6. A poppet valve 21 is located between the collars 18 and 19, the opposed aces of said collars being shaped to provide seats for said valve. The valve has a stem 22 extending upwardly through collar 19 and into collar 2O which serves as a guide for the upper end of said stem. A coiled spring 23 of suiciently strong and durable material, each as tungsten steel, surrounds the stem 22, the opposite ends of the spring bearing respectively againstthe collar 20 and against a pin 24 fixed transversely of the stem, so that the valve is normally seated upon the collar 18 and hence closes the passageway through the core. The stem 22 is so shaped that it does not close the apertures in the collars 19 and 20; it may be for example triangular in crosssection (seeFig. 5), so that it is guided in said collars without blocking the axial openings therethrough.

In order electrically to connect the. conductors 15 and 11, a freely movable circuitclosing element is preferably provided in the chamber 6, and in the illustrated embodiment. Said element comprises a pair of metal balls 25 movable longitudinally of the core conductor 11 and normally resting by action of gravity upon the collar 2O (Fig. 2). The diameter of each ol the balls is approximately the same as the diameter of the threaded'base of the conductor 11, so that the periphery of one or both of the balls is preferably in contact with the threads of the core at all times; yetY the balls should be free to reciprocate in the chamber in the manner hereinafter described. In the inoperative position shown in Fig. 2, the uppermost ball is spaced a substantial distance below the rod conductor 15 so that the vibration of the engine will not cause the balls to jump upwardly into premature contact with the base of said conductor, the balls being normally disposed in such position by action of gravity, as aforesaid. In their operative position (Fig. 3), thetopmost ball is in contact with the conductor 15 as well as with the core conductor 11, thus bridging the space between said conductors and completing the electrical circuit to cause an igniting spark to jump from the base of electrode 11 to the grounded electrode 17.

The valve 21 is movable between the seats of collars 18 and 19 against the action of spring 23. In normal or inoperative position (Fig. 2), the valve is seated upon collar 18; in operativeposition (Fig. 3) it is located between the collars 18 and 19 so that there is an open passageway from the base of the core 11 through collar 18, around valve 21, and through collars 19 and 2O to the chamber 6; and in another position the valve is seated against the collar 19 (Fig. 4) to close said passageway.

rlhe valve is actuated by gaseous pressure created in the cylinder by compression of the charge upon the upstroke of the piston. At the inomentiofhighest compression, that is, when the piston is in uppermost position and the cylinder is in firing condition, the accumulated pressure of the gaseous charge (which fills the open base of core 11) is suficient to overcome the resistance of spring 23 and the valve is accordingly lifted from its seat on collar 18. The compressed gases rush past the valve and through collars 19 and 2O and force the balls 25 upwardly into contact with conductor 15 (Fig. 3), thereby closing the circuit above described. The electric current jumps the gap between the base of the core conductor and the grounded electrode 17, igniting and exploding the compressed charge. The exploded gases then drive the valve 21 against its upper seat on collar 19, thus closing the passageway to chamber 6, so that the balls 25 are allowed to all away `from conductor 15 by action of gravity. After the exploded gases are expelled from the cylinder, upward pressure upon the valve is released and the valve is returned to its seat upon collar 18 (Fig. 2) by spring 2.3. This cycle of operation is repeated at each instant of highest compression in the respective cylinders, the strength of the spring being suliici'ent to hold the valve upon its lower seat until that instant.

It will be understood that the cycle of movement of the valve and the circuit closing balls is completed almost instantaneously, the balls 25 being forced upwardly approximately simultaneously with thefopening of valve 21, and dropping away from the end Vof rod conductor 15 immediately thereafter and falling far enough so that there is no danger of drawing a spark from the rod 15 which might cause the ignition of the incoming charge of the gaseous mixture.

A simple diagrammatic circuit for continually supplying potential to the spark plugs of a multi-cylinder engine such as that of an automobile is illustrated in Fig. 6 and comprises a battery 26 grounded to the frame at 27 and connected through a switch 28 and an associated vibrator or interrupter and induction coil shown as housed in common manner with a casing 29 to the spark plugs 30 by means of a common lead 31 which may be a flexible wire or a stiff bar. Itis thus apparent that the circuit is extremely simple and easy to install, and that the necessity of distributors ortiming devices, their electrical connections and'actuating mechanism, is obviated by this invention.

Y A spark plug constructed y as above Ydescribed is simple to manufacture andeasy to assemble ;v it may be made in the usual sizes and substituted for the plugs now in common use; and it has been found to be satisfactory and durable in operation. The assemblage of the valve and threaded collars within the metal corey 1l is facilitated by providing diametrical slots in the ends ofthe .respective collars as indicated at 32, 33 and 34 (Fig. 8). For example, the .collar 19 .may lirst be placed over the stem 22 of the valve and retained by pin 24,' and the collar may be threaded into the upper end of the core by engaging pin 24 inslot 33 and turning the stem by a suitable tool until the collar has reached its proper position; after applying spring 23, collar 2O may be screwed down upon the spring by a screw driver to exert propertension upon the spring; and collar 18 mayA then be threaded upwardly from the base of the tube against the valve. The core may be aiiiXed within the insulator 8 and the remaining elements of the plug may be assembled in any usual manner.

Although a preferred embodiment of the invention has been illustrated and particularly described hereabove, it will be 4understood that structural details of the spark plug may be varied to suitparticularcondi- Y tions and that the precise arrangement of the parts may be adjusted by experiment without departing from the essence of this invention as deined in the appended claims.

I claim:

1. In the cylinder of an internal combustion engine, a spark plug comprising a pair of stationary conductors permanently spaced from each other, a groundedy electrode in spark gap relation to one of the conductors, the other conductor being connected to a source of potential and normallybeinfrelectrically insulated from the iirst conductor, and means automatically operable in response to accumulated gaseous pressure in the cylinder for closing the icircuitbetween the conductors, said means including anelectrically .conductive member movable into simultaneous engagement with ,both of said conductors.

2. 11i-combination with the cylinder of an internal combustion engine, and an electric circuit for exploding the cylinder gases, Aa spark plug having a central chamber and comprising a pair of conductors normally electrically insulated from each other, portions o the respective conductors being arranged in spaced relation in said chamber so that the electric circuit between the conductors is normally open, one of the conductors being continually connected to a source of potentiaha grounded electrode in spark gap relation to theothericonduetorfa valve inthe spark plug movable in response to accumulated -gaseous pressure in the cylinder, and means controlled by movement of the valve for closing the circuit between the conductors.

3. In combination with the cylinder of an internal combustion engine, and an electric circuit for exploding the cylinder gases, a spark vplug having a central chamber and comprising a pair of conductors normally electrically insulated from each other, portions of the respective conductors being arranged in spaced relation in said chamber so that the electric circuit between the conductors is normally open, one of the conductors being connected with a source of potential, a .grounded electrode in spark gap relation to the other conductor, there being a passageway leading through the spark plug from the chamber tothe engine cylinder, a valve f in said passageway operable in response to accumulated gaseous pressure in the cylinder to admit the compressed gases to the chamber, and a circuit closing element movable in said chamber as a consequence of the admission of rsaid gases electrically to connect the conductors.

4. In combi-nation with the cylinderof an `internal combustion engine, and an velectric circuit `for exploding the cylinder gases, a spark plug having a central ,chamber and comprising a pair of conductors normally electrically insulated from each other, portions ofthe -respective conductors being arranged in spaced relation in said chamber so that the electric circuit between the conductors is normally open, one of the conductors being continually connected with a source of potential, a grounded electrode in spark gap relation to the conductor, a -member movable in the chamber into contact with the respective conductors thereby to close the circuit between the conductors, there .being a .passageway leading through the spark plug from said chamber to the engine cylinder to permit the admission of compressedrgases into the chamber, said member being moved to circuitV closing position as a consequence of the admi-ssionof said gases, and means for opening and closing the passageway, said means being operable in response to accumulated gaseous pressure in the cylinder.

5. In combination with the cylinderof an internal combustion engine, and an electric circuitv for exploding the cylinder gases, a spark plug having a central chamber and comprising a pair of conductors normally electrically insulated from each other, portions of the respective conductors being arranged in spaced relation in said chamber so that the -electrio circuit between the conductors is normally open, one of the Yconductors being continually connected to afsource of potential, a grounded electrode in spark gap relation to the conductor, a vmember moveen ablein the chamber into contact with the respective `conductors thereby to close the circuit between the conductors, there being a passageway leading through the spark plug from said chamber to the engine cylinder to permit the admission of compressed gases into the chamber, said member being moved to circuit'closing position as a consequence of the admission of said gases, a valve in said passageway, and resilient means normally holding the valve in closed position, the valve being opened in response to accumulated gaseous pressurein the cylinder.

6. In combination with the cylinder of an internal combustion engine, and an electric circuit for exploding the cylinder gases, a spark plug having a central chamber and comprising a pair of conductors normally electrically insulated from each other, portions oi" the respective conductors being arranged in spaced relation in said chamber so that the electric circuit between thev conductors is normally open, one of the conductors being continually connected to a source of potential, a grounded Velectrode in spark gap relation to the other conductor, there being a passageway leading through thesp'a'rk plug from the chamber to theengine cylinder, a valve in said passageway operable in response to accumulated gaseous pressure in the cyl inder successively to admit the compressed gases to thechamber and to interrupt the flow of said gases, and a member movable Within the chamber into contact with the respective conductors thereby to close the circuit between the conductors, said member being moved into circuit closing position by the admission of said gases to the chamber and falling away from the circuit closing position by action of gravity when the gases flow through thevpassageway is interrupted by said valve. f

7. A spark plug comprising a hollow ccnductor extending longitudinally through the lower portion 'of the plug and providing a central chamberand a passageway leading from said chamber to the base of the plug, agrounded electrode in spark gap relation to said conductor, a second conductor mount* ed lin the upper portion of the plug and normally electrically insulated from the first conductor, the second conductor being con tinually connected to a source of potential and having its lower end spaced fromthe bore of the first conductor withinsaid chamber, so that the circuit between said conductors is normally open, a circuit closing member freely movable in said chamber into lContact with the respective conductors upon the admission, of gaseous pressure through said passageway, a valve seat in the passage way, and a valve yieldably held upon said seat, the valve being movable away from its seat in response to gaseous pressure upon its base, thereby to admit gaseous pressure to said chamber.

8. A spark plug comprising a hollow conductor extending longitudinally through the lowerv portion of the plug and providing a central chamber and a passageway leading from said chamber to the base of the plug, a grounded electrode in spark gap relation to said conductor, a second conductor mounted in the upper portion of the plug and normally electrically insulated vfrom the first conductor, the second conductor being continually connected to a source of potential and having its lower endspaced from the bore of the first conductor within said chambers, so that the circuit between said conductors is normally open, a circuit closing member freely movable in said chamber into contact with the respective Vconductors upon the admission of gaseous pressure through said passageway, upper and lower valve seats in the passageway, a valve movable between said seats, and yielding means normally holding the valve upon the lower seat, said valve being automatically controlled by gaseous pressure upon its base.

9. A spark plug comprising a hollow conductor extending longitudinally through the lower portion of the plug and providing a central chamber and a passageway leading from said chamber to the base of the plug, a grounded electrode in spark gap relation to said conductor, a second conductor mounted inthe upper portion of the plug and normally electrically insulated from the first conductor, the second conductor being continually connected to a source of potential and having its lower end spaced from the bore of the lirst conductor within said chamber, so that the circuit between said conductors is normally open, a circuit closing member freely lmovable in said chamber into contact with the respective conductors upon the vadmission of gaseous pressure through said passageway,` upper and lower valve seats in the passageway, a valve movable between said seats, and yielding means normally holding the valve upon the lower seat, said valve being lautomatically controlled by gaseous pressure upon its base, and the circuit closing member being moved into circuit closing position by said gaseous pressure when the valve is moved away from its lower seat and falling away from said position by action of gravity when the pressure is interrupted by engagement of the valve with its upper seat.

10. A spark plug comprising a hollow conductor 'extending axially through the lower portion of the plug, and providing a central chamber and a passageway leading to the base of the plug, a grounded electrode in spark gap relation to said conductor, a second conductor mounted axially in the upper portion of the plug and normally electrically insulated from the first conductor, the second VIH conductor being connected to a source of potential and having its lower end projecting into said chamber in spaced relation to the bore of the first conductor, so that the circuit between said conductors is normally open, a series of removable collars disposed in spaced axial alignment in said passageway, a ball movable axially of said chamber into simultaneous contact with the bore of the first conductor and the end of the second conductor, the ball normally resting by action of gravity upon the `uppermost of said collars, a valve movable between the other two collars, said collars having opposed seats for the valve, the valve having a stem projecting inwardly of the passageway into the bore of the uppermost collar, and a coiled spring surrounding said stem and bearing against the last-named collar at one end and connected with the valve stem at its other end, thereby yieldingly to hold the valve upon the seat of the lowermost collar, said spring yielding in response to gaseous pressure upon the base of the valve to admit said pressure through the passageway thereby to propel the ball to circuit closing position.

Signed by me at Boston, Massachusetts, this 3rd day of December, 1929.

EDMUND E. PASTERIS. 

